Friday 14 September 2012 06.00 EDT
First published on Friday 14 September 2012 06.00 EDT

In accounts of all-consuming passions, the details can often overshadow an understanding of motivation. Adventure literature, in particular, is susceptible to this problem. The scale, risk and sense of awe involved in crossing oceans and polar ice caps or climbing mountains can make it hard to grasp why such feats are attempted in the first place. In the past decade or so a few mountaineering books have avoided this trap to tell us often unsettling things about the psychology of top climbers. Among them have been Kiss or Kill, the bleakly existential and angry memoir of self-described "punk-alpinist" Mark Twight, Johnny Dawes's Full of Myself and Andy Kirkpatrick's Psychovertical. If there is a thread linking these accounts, it is the depiction of a kind of awkwardness, the feeling of being out of step with the expectations and demands of ordinary life, usually experienced first at school. A gap filled by climbing.

This memoir from Nick Bullock is the latest addition to this short, if not exhaustive, list: an unusual and powerful story that is as remarkable for its depiction of the author's life as a prison officer in one of the country's toughest jails, Gartree, as for his prodigious achievements on the mountains. One of the world's best mountaineers (a fact confirmed by his recent ascent, the first by a British climber, of the dangerous and extremely demanding "Slovak route" on Denali, Alaska this summer), Bullock writes with a rare candour not just about his climbs but also about his political education in a violent world.

It is a book that grasps the attention immediately, as Bullock describes, in the shocking first few paragraphs, cradling a man's broken head in his hands, with "strings of cerebral fluid" making his knuckles wet. The scene is ambiguous just for a moment as the reader wonders if he is describing a climbing accident. But this is no accident. The man he is holding is a prisoner who has been struck on the head with a dumbbell in the gym after his drug-dealer training partner discovered he was a paedophile.

The story of Bullock's life and climbing career will come as a surprise to anyone whose notion of mountaineering has been informed by the British media over the past few years. For his is the antithesis of the usual tales of wealthy people being guided up Everest. Born into a working-class family in the Potteries, he struggles at school. His first job, as an underkeeper on a Welsh estate, leads to what sounds like a kind of breakdown, his teenage confidence brutally undermined by an episode of psychological bullying.

A series of dead-end jobs follow before he sits his entrance exam for the prison service. It is only then, in his 20s, that he discovers climbing, which acts as a liberation from the closed, hard world of the category A prison.

Not so long ago I heard a climber in his 50s talking about the notion of being a "lifer" – still going into the mountains well into middle age. And in an arresting section of this book, Bullock asks an uncomfortable question: what similarity is there between the recidivist criminals he encountered and climbers such as himself, who repeatedly court huge risks? "I wanted climbing," he writes. "I was prepared to put in the time and effort to gain the experience. But then, for repeat criminals, there's also the thrill of the chase, the uncertainty, the tension, the excitement – how much is that part of their drive? Crime or climb? Were they just two intoxicating drugs to get some of us through the sterility of modern life, the consumerism we learn in our schools, from parents and on TV?"

Indeed, as Bullock belatedly makes the transition from prison officer to full-time climber, he borrows images from prison to describe his climbs and uses his experiences of danger in the mountains as a metaphor for the violent life he encounters in the British jail system. In this, Bullock echoes the poet and critic Al Alvarez who, in his 1988 biography of his friend and sometime climbing partner, Mo Anthoine, talked of "feeding the rat" – borrowing Anthoine's own idea about climbing as a kind of self-medication.

This is a book driven by contrasts between the closed, enervating world of prison and the growing awareness and confidence Bullock feels on the mountains. In the end, the narrow scrapes, the friends Bullock loses and the exhilaration he feels on his solo winter climbs are all signposts on his road to self-liberation: the day he felt strong enough to resign from the prison service and walk out of jail for the last time.